The present invention relates to a method of manufacturing a magnetic head having a writing element for writing information into a recording medium by a perpendicular magnetic recording system and a reading element for reading out information recorded in the recording medium.
As a recording system for a magnetic recording and reproducing device have been known a longitudinal magnetic recording system in which the signal magnetization direction is set to a direction within the plane of a recording medium, and a perpendicular magnetic recording system in which the signal magnetization direction is set to a direction perpendicular to the plane of the recording medium. It is said that the perpendicular magnetic recording system is less influenced by thermal fluctuation of the recording medium as compared with the longitudinal magnetic recording system and thus can implement high linear recording density. Accordingly, the vertical magnetic recording system is expected to be practically used in the future.
The process of manufacturing a magnetic head by using the longitudinal magnetic recording system that are practically used at present contains:
(a) a step of forming plural magnetic head elements each containing a recording element for writing information into a recording medium and a reproducing element for reproducing information recorded in a recording medium while arranging the magnetic head elements on a wafer substrate;
(b) a step of cutting out the magnetic head elements from the wafer substrate every bar-shaped block comprising a predetermined number of magnetic head elements;
(c) a lapping step of polishing a floated surface of each block;
(d) a step of cutting each block into individual magnetic head elements; and etc.
In the lapping step of polishing the floated upper surface of the bar-shaped block, the polishing amount has been generally set from the viewpoint of adjusting the magnetic pole length (MR height) of the reproducing element. This is because slight magnetic force recorded in a recording medium is surely read out and thus the magnetic pole length of the reproducing element has a great effect.
Specifically, there has been hitherto adopted a method of using a measurement device for outputting a signal when the magnetic pole length of the reproducing element is set to a properly dimension, observing a signal from the reproducing element by using the measurement device while lapping the floated surface of the block and stopping the lapping work at the time point when the signal concerned is output from the reproducing element.
As described above, in the conventional lapping step, the polishing amount is set from the viewpoint of adjusting the magnetic pole length of the reproducing element, however, no attention has been paid to the magnetic pole length of the recording element. The reason for this is as follows. That is, the recording density is lower in the longitudinal magnetic recording system than that in the perpendicular magnetic recording system. Therefore, even when the magnetic pole length of the recording element is not strictly considered in the lapping step of the floated surface, it has little effect on the characteristic.
However, with respect to the magnetic head of the perpendicular magnetic recording system having higher recording density, developments to further enhance the recording density have been recently advanced.